Problem: Which of the following numbers is a multiple of 10? ${43,47,70,78,98}$
Solution: The multiples of $10$ are $10$ $20$ $30$ $40$ ..... In general, any number that leaves no remainder when divided by $10$ is considered a multiple of $10$ We can start by dividing each of our answer choices by $10$ $43 \div 10 = 4\text{ R }3$ $47 \div 10 = 4\text{ R }7$ $70 \div 10 = 7$ $78 \div 10 = 7\text{ R }8$ $98 \div 10 = 9\text{ R }8$ The only answer choice that leaves no remainder after the division is $70$ $ 7$ $10$ $70$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $10$ are contained within the prime factors of $70$ $70 = 2\times5\times7 10 = 2\times5$ Therefore the only multiple of $10$ out of our choices is $70$. We can say that $70$ is divisible by $10$.